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package funcs
import (
"fmt"
"net"
"github.com/apparentlymart/go-cidr/cidr"
"github.com/zclconf/go-cty/cty"
"github.com/zclconf/go-cty/cty/function"
"github.com/zclconf/go-cty/cty/gocty"
)
// CidrHostFunc contructs a function that calculates a full host IP address
// within a given IP network address prefix.
var CidrHostFunc = function.New(&function.Spec{
Params: []function.Parameter{
{
Name: "prefix",
Type: cty.String,
},
{
Name: "hostnum",
Type: cty.Number,
},
},
Type: function.StaticReturnType(cty.String),
Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
var hostNum int
if err := gocty.FromCtyValue(args[1], &hostNum); err != nil {
return cty.UnknownVal(cty.String), err
}
_, network, err := net.ParseCIDR(args[0].AsString())
if err != nil {
return cty.UnknownVal(cty.String), fmt.Errorf("invalid CIDR expression: %s", err)
}
ip, err := cidr.Host(network, hostNum)
if err != nil {
return cty.UnknownVal(cty.String), err
}
return cty.StringVal(ip.String()), nil
},
})
// CidrNetmaskFunc contructs a function that converts an IPv4 address prefix given
// in CIDR notation into a subnet mask address.
var CidrNetmaskFunc = function.New(&function.Spec{
Params: []function.Parameter{
{
Name: "prefix",
Type: cty.String,
},
},
Type: function.StaticReturnType(cty.String),
Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
_, network, err := net.ParseCIDR(args[0].AsString())
if err != nil {
return cty.UnknownVal(cty.String), fmt.Errorf("invalid CIDR expression: %s", err)
}
return cty.StringVal(net.IP(network.Mask).String()), nil
},
})
// CidrSubnetFunc contructs a function that calculates a subnet address within
// a given IP network address prefix.
var CidrSubnetFunc = function.New(&function.Spec{
Params: []function.Parameter{
{
Name: "prefix",
Type: cty.String,
},
{
Name: "newbits",
Type: cty.Number,
},
{
Name: "netnum",
Type: cty.Number,
},
},
Type: function.StaticReturnType(cty.String),
Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
var newbits int
if err := gocty.FromCtyValue(args[1], &newbits); err != nil {
return cty.UnknownVal(cty.String), err
}
var netnum int
if err := gocty.FromCtyValue(args[2], &netnum); err != nil {
return cty.UnknownVal(cty.String), err
}
_, network, err := net.ParseCIDR(args[0].AsString())
if err != nil {
return cty.UnknownVal(cty.String), fmt.Errorf("invalid CIDR expression: %s", err)
}
// For portability with 32-bit systems where the subnet number
// will be a 32-bit int, we only allow extension of 32 bits in
// one call even if we're running on a 64-bit machine.
// (Of course, this is significant only for IPv6.)
if newbits > 32 {
return cty.UnknownVal(cty.String), fmt.Errorf("may not extend prefix by more than 32 bits")
}
newNetwork, err := cidr.Subnet(network, newbits, netnum)
if err != nil {
return cty.UnknownVal(cty.String), err
}
return cty.StringVal(newNetwork.String()), nil
},
})
// CidrHost calculates a full host IP address within a given IP network address prefix.
func CidrHost(prefix, hostnum cty.Value) (cty.Value, error) {
return CidrHostFunc.Call([]cty.Value{prefix, hostnum})
}
// CidrNetmask converts an IPv4 address prefix given in CIDR notation into a subnet mask address.
func CidrNetmask(prefix cty.Value) (cty.Value, error) {
return CidrNetmaskFunc.Call([]cty.Value{prefix})
}
// CidrSubnet calculates a subnet address within a given IP network address prefix.
func CidrSubnet(prefix, newbits, netnum cty.Value) (cty.Value, error) {
return CidrSubnetFunc.Call([]cty.Value{prefix, newbits, netnum})
}
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